The background of the invention will be discussed in two parts:
1. Field of the Invention
This invention relates to flame simulating apparatus, and an incandescent lamp construction for use therewith, and more particularly to electronic apparatus for connection to one or more lamp devices for controlling the emissions thereof to simulate a candle light flame.
2. Description of the Prior Art
Flame simulating devices create a certain atmosphere which is warm and soothing. Attempts have been made to recreate the illusion in electrical lamp devices and apparatus. Such attempts have been directed to the dimming of conventional incandescent lamps, or the creation of special dedicated lamp bulbs which provide a "flickering" candle light effect.
One such dedicated lamp bulb is the gas-discharge type neon lamp, which is provided with two candle flame-shaped perforated electrodes encased within a neon gas-filled glass envelope. As the discharge occurs between the electrodes, the discharge path varies to simulate a candle light effect. In such a lamp device, the "flicker" effect is exaggerated, with the flicker intensity and brigthess being at a pre-set level determined by the characteristics of the electrode material and gas employed. In addition, the flicker parameters are poorly defined and not repeatable. With the use of neon, the color of the emitted light is not truly representative of the color of a flame, thus limiting the effectivity of the device as something akin to a candle light.
U.S. Pat. No. 3,790,998, shows and describes another dedicated lamp arrangement wherein the filament or light source is actually in motion. A long, flexible incandescent filament is looped about a centrally-located permanent magnet. AC-excited magnetic fields surrounding the energized filament set up a mechanical sympathetic resonance condition causing the filament to wildly swing back and forth past the central permanent magnet.
Other attempts at providing an atmosphere of dim or soothing light in an electrical lighting system have been directed at the "dimmer switches". Typically dimmer switches for incandescent lamps employ Triac controller devices for power control to the lamp controlled thereby. Generally, the main terminals of the Triac are connected in series with an AC circuit of one or more lighting branches. Triac gate triggering is commonly provided by an RC phase-shift network connected across the line, a capacitive charge storage element and a Diac to switch the charge into the Triac gate terminal once the required charge has accumulated.
The RC network time constant determines the phase angle where Diac break-off will occur, and this, in turn will switch the Triac "on" for some fractional portion of each complete half cycle of the alternating current source voltage. By selection of appropriate values, full-range light intensity control is possible using this approach. However, such circuits are simply attempts at controlling intensity, and do not have, as a purpose, the intent of simulating flame.
A more popular attempt at providing dimmed light is the conventional three-way light bulb. In such bulbs two unequal power independent filaments are enclosed inside one glass envelope to offer three different levels of total light output from one bulb dependnt on the combination of filaments energized, that is, one, the other ot both. Such lamps provide a low cost means for efficiently transitioning to one of three pre-set intensity, or brightness levels in accordance with lighting requirements, i.e., "reading" versus "general" lighting.
A more elaborate system exists at the Disneyland Park in California, a custom-fabricated system for providing flame simulation in street and interior lamps. Five relaxation oscillators utilizing neon lamps as their switching elements are adjusted to run at different frequencies from one another. The neon lamps are grouped in close proximity to a light-dependent resistor, such as a Cadmium Sulphide cell, which varies its resistance, or impedance, in accordance with the number and brightness of neon lamps firing at the same moment. The light-dependent resistor is effectively "looking" at several repetitively flashing light bulbs.
The light-dependent resistor is connected in series and shunt relation with other adjustable resistance elements to become a part of an RC phase-shift network similar to that described above. With such a system, the illumination and flicker is pre-set, with difficulty in modifying brightness and flicker intensity. The flicker characteristics are repetitive and not random as with a real flame, with extensive recalibration periodically required. In addition, due to the use of the light-dependent resistor, with its attendant characteristics modification on aging, flicker intensity is not well-defined, and unit-to-unit uniformity is difficult to obtain.
Accordingly, it is an object of the present invention to provide a new and improved flame simulating apparatus.
It is another object of the present invention to provide a new and improved electronic flame simulating apparatus for use with one or more lamp devices.
It is still another object of the present invention to provide a new and improved electronic flame simulating apparatus which provides for full-range dimming control as well as flicker intensity control.
It is yet another object of the present invention to provide a new and improved flame simulating apparatus which is voltage-controlled for stability and relative economy of construction.
It is a further object of the present invention to provide a new and improved flame simulating apparatus which is modular in construction, and may be used for one incandescent lamp, or for a set of such lamps, the apparatus having the capability of functioning as a conventional dimmer system.
It is still another object of the present invention to provide a new and inproved lamp device for simulating a moving candle flame.
It is a still further object of the present invention to provide a new and improved multiple filament lamp device for use in the flame simulating apparatus to simulate a moving candle flame.